Optical sensor capable of detecting ir light and visible light simultaneously

ABSTRACT

An optical sensor includes an image sensor, a proximity sensor and a visible light sensor. The image sensor includes a first pixel and a second pixel. The first pixel is coated with a first optical film for blocking light whose wavelength is outside a first predetermined range and a second optical film for blocking light whose wavelength is outside a second predetermined range. The proximity sensor generates an IR signal according to a first exposure value. The visible light sensing unit generates a visible light signal according to the difference between the first exposure and a second exposure value or according to a ratio of the first exposure value to the second exposure value. The first exposure value represents an incident light quantity which is absorbed by the first pixel. The second exposure value represents an incident light quantity which is absorbed by the second pixel.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 13/427,912, filed Mar. 23, 2012.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to an optical sensor, and moreparticularly, to an optical sensor capable of detecting IR light andvisible light simultaneously.

2. Description of the Prior Art

Light is the portion of electromagnetic radiation whose wavelength isbetween 300 nm (ultraviolet) to 14,000 nm (far infrared). The wavelengthof visible light lies in a range from about 380 to about 780 nm.Infrared radiation (IR) is the portion of electromagnetic radiationwhose wavelength is between 780 nm to 1400 nm. With high thermalefficiency, strong penetration and easy absorption, IR imaging is usedextensively for communication, probing, medical and military purposes.

An optical sensor is used for converting optical signals into electricalsignals using an image sensor capable of detecting light in a wavelengthrange of 400-1000 nm. Visible light sensors are commonly used forcontrolling environmental brightness. IR sensors, also called proximitysensors, are often used for surveillance purposes.

FIG. 1 illustrates the optical spectrum measured by a prior art visiblelight sensor. Curves R, G and B represent the transmittance-wavelengthcharacteristics of the red, green and blue visible light, respectively.As previously explained, human eyes are unable to perceive invisiblelight whose wavelength is larger than 780 nm. However, the prior artvisible light sensor may detect peaks in the non-visible range of theoptical spectrum which results in inaccurate results. For example, whenthe intensity of ambient light becomes insufficient to human eyes, theprior art visible light sensor may provide an inaccurate result ofsufficient ambient light due to the detection of invisible light.Therefore, optical sensors are required to simultaneously includefunctions of the visible light sensor and the proximity sensor in manyapplications.

In US Patent Application No. US 2006/0180886, a visible light sensorhaving a multi-layer filter structure by alternatively fabricating Agand Si3N4 layers on an optical device is disclosed. The thickness ofeach layer in the multi-layer filter structure is determined accordingto Fabry-Perot interference principle so that each region of the opticaldevice may detect a specific wavelength range for blocking IR light.However, this prior art requires complicated manufacturing processeswhich may reduce product yield or increase manufacturing costs.

SUMMARY OF THE INVENTION

The present invention provides an optical sensor including an imagesensor and a processing unit. The image sensor includes a first pixeland a second pixel. The first pixel is coated with a first optical filmconfigured to block light whose wavelength is outside a firstpredetermined range and a second optical film configured to block lightwhose wavelength is outside a second predetermined range. The processingunit is configured to simultaneously receive pixel data measured by thefirst pixel and the second pixel and generate an electrical signalaccordingly.

The present invention also provides an optical sensor including an imagesensor and a processing unit. The image sensor includes a first pixeland a second pixel. The first pixel is coated with a first optical filmconfigured to block light whose wavelength is outside a firstpredetermined range and a second optical film configured to block lightwhose wavelength is outside a second predetermined range. The secondpixel is coated with a third optical film configured to block lightwhose wavelength is outside a third predetermined range. The processingunit is configured to simultaneously receive pixel data measured by thefirst pixel and the second pixel and generate an electrical signalaccordingly.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the optical spectrum measured by a prior art visiblelight sensor.

FIGS. 2A-2C are diagrams illustrating optical sensors according to afirst embodiment of the present invention.

FIG. 3 is the optical spectrum associated with the IR electrical signalgenerated by the present optical sensor.

FIG. 4 is the optical spectrum associated with the visible lightelectrical signal generated by the present optical sensor.

FIGS. 5A-5C are diagrams illustrating optical sensors according to asecond embodiment of the present invention.

FIG. 6 is the optical spectrum associated with the red visible lightelectrical signal generated by the present optical sensor.

FIG. 7 is the optical spectrum associated with the green visible lightelectrical signal generated by the present optical sensor.

FIG. 8 is the optical spectrum associated with the blue visible lightelectrical signal generated by the present optical sensor.

DETAILED DESCRIPTION

For ease and clarity of explanation, elements which are not directlyassociated with the present invention are omitted when describingpreferred embodiments of the present invention. Meanwhile, the size andlocation of each described device are merely for illustrative purposeand do not intend to limit the scope of the present invention.

FIGS. 2A-2C are diagrams illustrating optical sensors 100A-100Caccording to a first embodiment of the present invention. Each of theoptical sensors 100A-100C includes an image sensor 10, a proximitysensor SR_(IR), and a visible light sensor SR_(RGB). The image sensor 10includes a pixel P1 coated with two types of optical films and a pixelP2 without any coating. The pixels P1 and P2 of the image sensor 10 mayabsorb light and generate corresponding electrical signals. Theproximity sensor SR_(IR) and the visible light sensor SR_(RGB) aresignal processors capable of determining the intensity of visible lightor IR light according to the electrical signals received from the pixelsP1 and P2.

In the optical sensor 100A according to the first embodiment of thepresent invention, the pixel P1 is coated with a red optical film C_(R)and a blue optical film C_(B), wherein the red optical film C_(R) onlytransmits the red visible light (i.e. blocking light whose wavelength isnot between 600-780 nm) and the blue optical film C_(B) only transmitsthe blue visible light (i.e. blocking light whose wavelength is notbetween 380-500 nm). The blue optical film C_(B) may block the redvisible light after it passes through the red optical film C_(R), whilethe red optical film C_(R) may block the blue visible light after itpasses through the blue optical film C_(B). Therefore, regardless of thesequence of fabricating the red optical film C_(R) and the blue opticalfilm C_(B) on the pixel P1, only the IR light can reach the pixel P1.FIG. 2A only illustrates an embodiment of the present invention. Thesequence of fabricating the red optical film C_(R) and the blue opticalfilm C_(B) on the pixel P1 does not limit the scope of the presentinvention.

In the optical sensor 100B according to the first embodiment of thepresent invention, the pixel P1 is coated with a red optical film C_(R)and a green optical film C_(G), wherein the red optical film C_(R) onlytransmits the red visible light (i.e. blocking light whose wavelength isnot between 600-780 nm) and the green optical film C_(G) only transmitsthe green visible light (i.e. blocking light whose wavelength is notbetween 500-600 nm). The green optical film C_(G) may block the redvisible light after it passes through the red optical film C_(R), whilethe red optical film C_(R) may block the green visible light after itpasses through the green optical film C_(G). Therefore, regardless ofthe sequence of fabricating the red optical film C_(R) and the greenoptical film C_(G) on the pixel P1, only the IR light can reach thepixel P1. FIG. 2B only illustrates an embodiment of the presentinvention. The sequence of fabricating the red optical film C_(R) andthe green optical film C_(G) on the pixel P1 does not limit the scope ofthe present invention.

In the optical sensor 100C according to the first embodiment of thepresent invention, the pixel P1 is coated with a green optical filmC_(G) and a blue optical film C_(B), wherein the green optical filmC_(G) only transmits the green visible light (i.e. blocking light whosewavelength is not between 500-600 nm) and the blue optical film C_(B)only transmits the blue visible light (i.e. blocking light whosewavelength is not between 380-500 nm). The green optical film C_(G) mayblock the red visible light after it passes through the red optical filmC_(R), while the red optical film C_(R) may block the green visiblelight after it passes through the green optical film C_(G). Therefore,regardless of the sequence of fabricating the green optical film C_(G)and the blue optical film C_(B) on the pixel P1, only the IR light canreach the pixel P1. FIG. 2C only illustrates an embodiment of thepresent invention. The sequence of fabricating the green optical filmC_(G) and the blue optical film C_(B) on the pixel P1 does not limit thescope of the present invention.

As previously explained, after absorbing the incident IR light after itpasses through two types of optical films, an incident light quantityabsorbed by the pixel P1 is represented by a first exposure value EX1.After absorbing the incident IR light and the visible light, an incidentlight quantity absorbed by the pixel P2 is represented by a secondexposure value EX2. The proximity sensor SR_(IR) is configured togenerate an IR electrical signal S_(IR) according to the exposure valueEX1. The visible light sensor S_(RGB) is configured to generate avisible light electrical signal S_(RGB) according to the differencebetween the exposure values EX1 and EX2 or according to the ratio of theexposure value EX1 to the exposure value EX2. The exposure values EX1,EX2 and the electrical signals S_(IR), S_(RGB) may be voltage signals orcurrent signals.

FIG. 3 illustrates the optical spectrum associated with the IRelectrical signal S_(IR) generated by the optical sensors 100A-100C.FIG. 4 illustrates the optical spectrum associated with the visiblelight electrical signal S_(RGB) generated by the optical sensors100A-100C. The vertical axis represents transmittance (%), and thehorizontal axis represents wavelength (nm). In the optical sensors100A-100C of the present invention, the intensity of the IR light may bemeasured by the proximity sensor SR_(IR), and the intensity of thevisible light may be measured by the visible light sensor SR_(RGB).

FIGS. 5A-5C are diagrams illustrating optical sensors 200A-200Caccording to a second embodiment of the present invention. Each of theoptical sensors 200A-200C includes an image sensor 10, a proximitysensor SR_(IR), a red visible light sensor SR_(R), a green visible lightsensor SR_(G), and a blue visible light sensor SR_(B). The image sensor10 includes four pixels P1-P4: the pixel P1 is coated with two types ofoptical films, while each of the pixels P2-P4 is coated a specific typeof optical film. The pixels P1-P4 of the image sensor 10 may absorblight and generate corresponding electrical signals. The proximitysensor SR_(IR), the red visible light sensor SR_(R), the green visiblelight sensor SR_(G), and the blue visible light sensor SR_(B) are signalprocessors capable of determining the intensity of each visible light orIR light according to the electrical signals received from the pixelsP1-P4.

In the optical sensor 200A according to the second embodiment of thepresent invention, the pixel P1 is coated with a red optical film C_(R)and a blue optical film C_(B). In the optical sensor 200B according tothe second embodiment of the present invention, the pixel P1 is coatedwith a red optical film C_(R) and a green optical film C_(G). In theoptical sensor 200C according to the second embodiment of the presentinvention, the pixel P1 is coated with a green optical film C_(G) and ablue optical film C_(B). The red optical film C_(R) only transmits thered visible light (i.e. blocking light whose wavelength is not between600-780 nm). The green optical film C_(G) only transmits the greenvisible light (i.e. blocking light whose wavelength is not between500-600 nm). The blue optical film C_(B) only transmits the blue visiblelight (i.e. blocking light whose wavelength is not between 380-500 nm).As previously explained, a specific type of visible light capable ofpassing through a specific optical film may be blocked by another typeof optical film. Therefore, regardless of the sequence of fabricatingthe red optical film C_(R), the green optical film C_(G) or the blueoptical film C_(B) on the pixel P1, only the IR light can reach thepixel P1. FIGS. 5A-5C only illustrate embodiments of the presentinvention. The sequence of fabricating the red optical film C_(R), thegreen optical film C_(G) and the blue optical film C_(B) on the pixel P1does not limit the scope of the present invention.

Meanwhile, in the optical sensors 200A-200C according to the secondembodiment of the present invention, the pixel P2 is coated with a redoptical film C_(R), the pixel P3 is coated with a green optical filmC_(G), and the pixel P4 is coated with a blue optical film C_(B). Thered optical film C_(R) only transmits the red visible light (i.e.blocking light whose wavelength is not between 600-780 nm). The greenoptical film C_(G) only transmits the green visible light (i.e. blockinglight whose wavelength is not between 500-600 nm). The blue optical filmC_(B) only transmits the blue visible light (i.e. blocking light whosewavelength is not between 380-500 nm). Therefore, only the red visiblelight can reach the pixel P2, only the green visible light can reach thepixel P3, and only the blue visible light can reach the pixel P4.

As previously explained, after absorbing the incident IR light after itpasses through two types of optical films, an incident light quantityabsorbed by the pixel P1 is represented by a first exposure value EX1.After absorbing the incident IR light and the red visible light passingthrough one optical film, an incident light quantity absorbed by thepixel P2 is represented by a second exposure value EX2. After absorbingthe incident IR light and the green visible light passing through oneoptical film, an incident light quantity absorbed by the pixel P3 isrepresented by a third exposure value EX3. After absorbing the incidentIR light and the blue visible light passing through one optical film, anincident light quantity absorbed by the pixel P4 is represented by afourth exposure value EX4. The proximity sensor SR_(IR) is configured togenerate an IR electrical signal S_(IR) according to the exposure valueEX1. The red visible light sensor SR_(R) is configured to generate a redvisible light electrical signal S_(R) according to the differencebetween the exposure values EX1 and EX2 or according to the ratio of theexposure value EX1 to the exposure value EX2. The green visible lightsensor SR_(G) is configured to generate a green visible light electricalsignal S_(G) according to the difference between the exposure values EX1and EX3 or according to the ratio of the exposure value EX1 to theexposure value EX3. The blue visible light sensor SR_(B) is configuredto generate a blue visible light electrical signal S_(B) according tothe difference between the exposure values EX1 and EX4 or according tothe ratio of the exposure value EX1 to the exposure value EX4. Theexposure values EX1-EX4 and the electrical signals S_(IR), S_(R), S_(G),and S_(B) may be voltage signals or current signals.

FIG. 3 also illustrates the optical spectrum associated with the IRelectrical signal S_(IR) generated by the optical sensors 200A-200C.FIG. 6 illustrates the optical spectrum associated with the red visiblelight electrical signal S_(R) generated by the optical sensors200A-200C. FIG. 7 illustrates the optical spectrum associated with thegreen visible light electrical signal S_(G) generated by the opticalsensors 200A-200C. FIG. 8 illustrates the optical spectrum associatedwith the blue visible light electrical signal S_(B) generated by theoptical sensors 200A-200C. The vertical axis represents transmittance(%), and the horizontal axis represents wavelength (nm). In the opticalsensors 200A-200C of the present invention, the intensity of the IRlight may be measured by the proximity sensor SR_(IR), and the intensityof each visible light may be measured by the corresponding visible lightsensor SR_(R), SR_(G), and SR_(R).

In conclusion, the optical sensor according to the present inventiononly requires simple manufacturing process, and can provide functions ofthe proximity sensor and the visible light sensor using differentoptical films.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

1. An optical sensor, comprising: an image sensor, comprising: a firstpixel coated with two optical films, wherein: a first optical film isconfigured to provide first transmittance for light whose wavelength isoutside a first predetermined range and provide second transmittance forlight whose wavelength is within the first predetermined range; and asecond optical film is on the first optical film and configured toprovide third transmittance for light whose wavelength is outside asecond predetermined range and provide fourth transmittance for lightwhose wavelength is within the second predetermined range; and a secondpixel without being coated with any optical film, the first pixel andthe second pixel being disposed on a same substrate within the imagesensor; and a processing unit configured to receive pixel data measuredby the first pixel and the second pixel, wherein: the firstpredetermined range and the second predetermined range are notoverlapped; the first transmittance is smaller than the secondtransmittance; the third transmittance is smaller than the fourthtransmittance; and the optical sensor provides functions of a proximitysensor and a visible light sensor.
 2. The optical sensor of claim 1,wherein the first predetermined range and the second predetermined rangeare different and selected from 380-500 nm, 500-600 nm, and 600-780 nm.3. The optical sensor of claim 1, wherein the processing unit comprisesthe proximity sensor configured to generate an infrared radiation (IR)electrical signal according to a first exposure value, wherein the firstexposure value represents an incident light quantity which is absorbedby the first pixel.
 4. The optical sensor of claim 1, wherein theprocessing unit comprises the visible light sensor configured togenerate a visible light electrical signal according to a differencebetween a first exposure value and a second exposure value or accordingto a ratio of the first exposure value to the second exposure value,wherein the first exposure value represents an incident light quantitywhich is absorbed by the first pixel, and the second exposure valuerepresents an incident light quantity which is absorbed by the secondpixel. 5-6. (canceled)